This kind of device usually comprises a U-shaped arch that has a lower surface on the lower jaw side and an upper surface on the upper jaw side, both of which have teeth receiving concaves. The device is made of a flexible and elastic material, such as a thermoplastic elastomer, plasticized (softened) plastic or rubber or of a similar material.
The invention, furthermore, relates to an occlusion guidance device series as well as a method for selecting a device for occlusion guidance in orthodontic treatment. In the method, at least one characteristic measurement is defined for a person's teeth, and an appropriate device is selected for the person based on this measurement.
The treatment method by which to achieve the required occlusion is also described in the description of the invention.
Odontological occlusion guidance appliances, orthodontic braces and equivalent odontological devices are used fairly commonly to treat and eliminate problems such as supraocclusion, rotations and individual cross-bites. Previously known devices are dental braces made of steel and teeth positioning devices made of flexible materials. In the latter ones, i.e. the (so-called) occlusion guidance appliances, there are typically concaves for the teeth of the lower and upper jaw that are separated by an isthmus that has recesses, so-called “blanks”, formed for the individual teeth. With these blanks individual teeth can be guided to the required place and position. Devices of a kind, where a part of said blanks has been replaced with compartments intended for more than one tooth, are also known. The devices have been designed and are meant to be used mainly during the phase when the milk teeth are being replaced by adult teeth and after the adult teeth have erupted. The occlusion guidance appliances are meant to be used passively, particularly during the night, but in difficult or complex cases they are recommended to be used also for 1-4 hours during the daytime. The manufacturing material in the known technology has normally been plasticized (softened) polyvinyl chloride.
Occlusion guidance appliances have been presented, for example, in published patent applications nos. WO 02/062253 and WO 02/062252, FR Patent Specification No. 1 104897 as well as in U.S. Pat. Nos. 4,784,605, 4,799,884, 4,830,612, 4,919,612 and 5,879,199, the contents of which are herewith incorporated by reference.
U.S. Pat. No. 4,830,612 presents an occlusion guidance appliance designed for children of ages 2-6, where the incisors, canine teeth and the first middle teeth each have their own blanks. A single, continuous and uniform compartment has then been formed for the second middle tooth and first molars. The device is meant to be used before the milk teeth come out and is appropriate only for the milk teeth, since the device ends before the second molar. In the description and the claims it has been emphasized that the device should at a maximum extend to the point where the first molar will erupt. This kind of device cannot be recommended for use by older children, because there is a danger that the second molar will over-erupt and cause an open occlusion. If one wants to continue the treatment of the patient even after the permanent teeth have erupted, the device must be replaced by another device designed for that phase of development. The use of many different kinds of occlusion guidance appliances will be expensive for the patient and will require the manufacturer and the dentist to have a wide range of products.
In addition to the above-mentioned problems, there are also other disadvantages related with the known solutions. Typically, it is difficult to get the occlusion guidance appliance to remain in the correct position in the mouth, for example, when the person is sleeping and the lower jaw very easily “drops” and retracts somewhat. This could lead to the patient biting the device from the inside of the lower edge, in which case the device is not working as it should, and is in fact guiding the positioning of teeth towards a different direction than originally intended. In addition, the device, if not properly positioned in the mouth, may be easily bitten during daily use to the point where it breaks.
In WO Publications Nos. 02/1062253 and 02/1062252 a device is disclosed, which is meant for positioning the teeth and in which the inner wall of the lower jaw side concave extends downwards in such a way that it forms a tongue ramp. This is designed to partially encircle the tongue from underneath. The publication has no mention of using the tongue ramp, for example, to further the stationary position of the occlusion guidance appliance.
Further, the problem in known solutions is that the occlusion guidance appliances have been designed to be used in a particular developmental phase of the teeth. In this case, the device to be used has to be chosen not only according to the size of the teeth but also from a variety of different devices. On top of the problems of selecting the device and the frequency of changing it, there is also the added costs arising from a need to maintain a large range of products.